Nonwoven material and method of manufacture therefor

ABSTRACT

A flexible, recyclable and sewable nonwoven textile formed from first fibers having a high temperature polyester core and a low temperature thermoplastic sheath, and second thermoplastic fibers formed from a high temperature polyester. The nonwoven textile is formed by blending the first thermoplastic staple with the second thermoplastic staple, carding the blend into a web, cross lapping the fibers of the web into a mat, needling the mat, heating the mat to a temperature above the melt temperature of the low temperature thermoplastic thereby forming unions between the fibers.

BACKGROUND

[0001] The present invention generally relates to nonwoven textiles, andin particular, to recyclable nonwoven textiles that are sewable.

[0002] Nonwoven textiles are typically produced by making a mat offibers, and securing those fibers together to form a textile. The fibersof the mat can be secured together through mechanical connecting,adhesive bonding, or thermal fusing.

[0003] Nonwoven textiles are used in various applications such asbacking material for fabrics in automotive applications or as a standalone textile. To be used as a backing material for fabrics, thematerial will have properties that enable the ease of sewing thematerial. Additionally, there has been a recent interest in using onlymaterials that are recyclable for applications such as automotive use.Therefore, it is one objective of the current invention to produce anonwoven textile that is recyclable and has desirable sewabilitycharacteristics.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] These and other features, aspects, and advantages of the presentinvention will become better understood with regard to the followingdescription, appended claims, and accompanying drawings where:

[0005]FIG. 1 shows an enlarged cross-section of a nonwoven materialillustrating one embodiment of the present invention;

[0006]FIG. 2 shows an enlarged cross-section of a first fiber from thenonwoven material in FIG. 1;

[0007]FIG. 3 shows a block diagram of a process for forming the nonwovenin FIG. 1; and

[0008]FIG. 4 shows a test sample of an example material that has beenfolded open.

DETAILED DESCRIPTION

[0009] Referring now to the figures, and in particular to FIG. 1, thereis shown an enlarged cross-sectional view of a nonwoven textile 10illustrating an embodiment of the present invention. The nonwoventextile 10 is highly flexible, which facilitates its ability to be usedas a backing material for fabrics. The nonwoven textile 10 is also arecyclable and sewable material. The nonwoven textile also has superiorseam strength. These properties permit the use of the nonwoven textile10 as a backing material for fabrics such as fabrics used in automotiveapplications.

[0010] What is meant by “flexible” is that the material will tend tobend or fold over under its own weight when held horizontal.

[0011] What is meant by “recyclable” is that the item is made up ofmaterials of the same or similar chemical nature which can be convertedinto the basic raw material status for use in forming new items.

[0012] What is meant by “sewability” or “sewable” is that the materialis easily penetrated by a sewing needle and stitched with a thread.

[0013] What is meant by seam strength, is the ability of a material toretain its strength at a seam. The tensile strength of a materialcontributes to seam strength. One method of testing seam strength is tomeasure the gap between two sections of the material that have been sewntogether, after having subjected the sewn together material to aspecific number of flex cycles. In another method of testing seamstrength, the ultimate tensile strength of two sections of material sewntogether, after having subjected the sewn together material to aspecific number of flex cycles.

[0014] The nonwoven textile 10 generally comprises a plurality of firstfibers 20 intermixed with a plurality of second fibers 30. As shown inFIG. 2, the first fibers 20 generally include a core material 21 and asheath material 22. The core material 21 and the sheath material 22 ofthe first fibers 20 are preferably a thermoplastic, and more preferably,a thermoplastic that is recyclable such as polyester. Additionally, thecore material 21 of the first fibers 20 has a higher melting point thanthe sheath material 22. The second fibers 30 are also preferably athermoplastic material, and more preferably, a recyclable thermoplasticmaterial such as polyester. The material of the second fibers 30 has ahigher melting point than the sheath material 22 of the first fibers 20.

[0015] The first fibers 20 and the second fibers 30 are intertwinedwithin the nonwoven textile 10 through a process of needle punching.Additionally, at various crossing points of various first fibers 20 andthe crossing of first fibers 20 with second fibers 30, a bond point 11is created between the crossing fibers 20, 30, due to the melt fusing ofthe sheath material 22 in the first fibers 20.

[0016] The nonwoven textile 10 is preferably 4-15 ounces per squareyard, and includes a ratio of from about five to about twenty percent(5-20%) by weight of the first fibers 20 to the total weight of thecombination of the first fibers 20 and the second fibers 30. The sheathmaterial 22 of the first fibers 20 is preferably a low melt temperaturethermoplastic, such as a low melt temperature polyester, that is betweenabout 5 to about 15% of the total weight of the first fiber 20. The corematerial 21 of the first fiber 20 is preferably a high melt temperaturethermoplastic, such as a high melt temperature polyester, that isbetween about 85 to about 95% of the total weight of the first fiber 20.The first fiber 20 is also preferably between about 4-6 denier. Thesecond fiber 30 is preferably a high melt temperature polyester having adenier between about 3-12. The first fibers 20 and the second fibers 30are mechanically locked with needle punches of between about 1100 andabout 1800 punches per square inch.

[0017] Referring now to FIG. 3, there is shown a block diagramillustrating one embodiment of a method for forming the nonwoven textile10 in FIG. 1. In the process illustrated in FIG. 3, the first fibers 20are supplied from a first fiber supply 111, and second fibers 30 aresupplied from a second fiber supply 112. The first fibers 20 and thesecond fibers 30 are blended in a blending step 120 with a ratio of fromabout five to about twenty percent (5-20%) by weight of the first fibers20 to the total weight of the combination of first fibers 20 and secondfibers 30. The blended fibers from step 120 are carded into a web formin the carding step 130. The web from the carding step 130 is crosslapped in cross lapping step 140 to insure crossing of the variousfibers into a mat.

[0018] After the cross lapping step 140, the mat is needled in theneedling step 150. The needling step 150 creates between about 1100 andabout 1800 punches per square inch to entangle and mechanically locktogether the fiber of the mat. After the mat has been cross lapped inthe cross lapping step 140, and needled in the needling step 150, themat is subjected to heat in a heating step 160. The heating step 160brings the fibers in the mat to a temperature greater than the lowermelt temperature of the sheath material 22 in the first fibers 20,thereby softening the sheath material. During the heating step 160,adjacent second fibers 30 embed into the softened sheath material 22 ofthe first fibers 20, and sheath material 22 of adjacent first fibers 20intermix, thereby forming bond points 11. After the mat is heated to atemperature to form bond points 11 between fibers, the mat is cooled ina cooling step 170 below the melting point of the sheath material toproduce the nonwoven textile 10.

[0019] In one example, a first fiber having a core of high meltpolyester and a sheath of low melt polyester is combined with secondfibers of a high melt polyester. The high melt polyester core of thefirst fiber is about 90% of the weight of the first fiber. The firstfiber was about a 4 denier fiber. The second fiber was about a 6 denierfiber. The first fibers and the second fibers were blended with a ratioof about five percent (5%) to about twenty percent (20%) by weight ofthe first fibers 10 to the total weight of the combined first fibers 10and the second fibers 30. After the fibers were blended into a mat,carded, and cross lapped, the mat was needled punched at the rate ofabout 1,650 punches per inch. After needling, the mat was subjected to atemperature of between about 275° and about 305° for a period of about180 seconds. The high temperature was sufficient to cause the sheathmaterial of the first fiber to flow around adjoining fibers and formrandom point bonds in the material. The resulting material became arecyclable nonwoven textile of polyester that is flexible and easier tosew than current technology.

[0020] Various samples of the example material were measured for tensilestrength by measuring the elongation when about a 120 N (27 lb) forcewas applied across about a 76.2 mm (inches) wide sample. Samples testedwith the force applied in the machine direction of the materialexperienced between about 6.3% and about a 8.3% elongation during theapplication of the force, and between about a 2.1% and about a 3.1%permanent elongation. Samples tested with the force applied along thecross direction of the material experienced between about 3.4% and about9.4% elongation during the application of the force, and between about a1.0% and about a 3.1% permanent elongation.

[0021] To test the seam strength of the material from the example above,sections of the example material above were sewn together into varioustest sample using 58N (13 lb.) test nylon thread, Material StandardMS-JZ3-2, with a No. 22 size sewing needle at about 0.24 stitches/mm (6stitches/in.). Two sections 210 and 220 of the example material wereconfigured into the test samples 200 according to FIG. 4. The twosections 210/220 of example material are sewn together at the seam 230with the facing surfaces F1 and F2 contacting each other, and thenfolded open to the configuration in FIG. 4. Each section 210/220includes tabs 211 and 221 with grasping points 212 and 222.

[0022] The seam of various test samples were subjected to 10,000 cyclesof flex for measuring the seam strength. Each cycle of flex isaccomplished by grasping the grasping points of each tab 210/220, movingone of the two the grasping points 34.9 mm (1.375 inches) opposite ofthe other grasping point laterally along the seam 230 with 35.59 N (8lbs) force at 42 cycles per minute. Each cycle produces a total of 139.6mm (5.5 inches) movement of the grasping points 210/220 along the seam230 (34.9 mm from center in each direction and back).

[0023] Various samples of the example material were tested for the gapbetween the two sections at the seam after being subjected to the flexcycles. After the flex cycles, the gap between the two sections ofmaterial at the seams was about 1.0 mm (0.039 inches) or less for seamsacross the machine direction of the material, and the gap was about 1.5mm (0.059 inches) or less for seams across the cross direction of thematerial.

[0024] Various samples of the example material were also tested for thestrength of the material at the seam after being subjected to the flexcycles. After the cycles of flex, an increasing load was applied to thegrasping points 210/220 across the seam 230 of the test sample accordingto FIG. 1, until failure occurred. No failure of the of the examplematerial adjacent to the seam was notice when a load of about 720 N (164lb) or greater was applied to a sample having the seam across themachine direction of the example material, or when a load of about 1030(231.5 lb) or greater was applied to a sample having the seam across thecross direction of the example material.

[0025] Although the present invention has been described in considerabledetail with reference to certain preferred versions thereof, otherversions are possible. Therefore, the spirit and scope of the appendedclaims should not be limited to the description of the preferredversions contained herein.

What is claimed is:
 1. A nonwoven material comprising a plurality offibers intermingled and fused together, said fibers being formed of arecyclable material, and wherein said nonwoven material is sewable. 2.The nonwoven according to claim 1, wherein said nonwoven material isflexible.
 3. The nonwoven according to claim 1, wherein said recyclablematerial comprises a thermoplastic material.
 4. The nonwoven accordingto claim 3, wherein said fibers are polyester.
 5. The nonwoven accordingto claim 1, wherein said fibers are entangled through needlepunching. 6.The nonwoven according to claim 1, wherein the fibers of said nonwovenmaterial comprise a first fiber having an exterior portion with a firstmelt temperature, and a second fiber having a second melt temperature,wherein said first melt temperature is lower than said second melttemperature.
 7. The nonwoven according to claim 6, wherein said fibersare entangled through needlepunching.
 8. The nonwoven according to claim6, wherein the exterior portion of said first fiber comprises a sheathhaving the first melt temperature and said first fiber further comprisesa core having a core melt temperature, and wherein said core melttemperature is higher than said first melt temperature.
 9. The nonwovenaccording to claim 8, wherein said fibers are entangled throughneedlepunching.
 10. A method for forming a nonwoven material includingthe steps of: (a) blending a first thermoplastic staple fiber having anouter area with a first melting point with a second thermoplastic staplefiber having a higher second melting point; (b) carding the blend of thefirst thermoplastic staple fiber and the second thermoplastic staplefiber into a web; (c) crosslapping the fibers of the carded web into amat; (d) needle punching the cross lapped mat to entangle the fibers ofthe mat; (e) heating the mat to a temperature above the first meltingpoint of the first thermoplastic staple fiber until at least a portionof the first thermoplastic staple fibers form a union with other firstthermoplastic staple fibers and second thermoplastic staple fibers; and,(f) cooling the mat below the first melting temperature of the firstthermoplastic staple fibers.
 11. The method according to claim 10,wherein the first thermoplastic staple fiber has a core and a sheath,the sheath having the first melting point and the core having a meltingpoint higher than the first melting point.
 12. The method according toclaim 10, wherein said step of needling includes the step of needlingbetween 1100-1800 punches per inch.